What am I paying for

My car is currently at Barons N1 city, because they service my car and are the agents for VW. 2016 I had my car serviced and I was called to say my brake fluid & windscreen wipers need to be replaced, because of the ridiculous price, I said I will have it done myself. 2017 I have my car serviced, still haven't changed my wipers, but nobody advised this time that I need to replace it, so was it faulty in 2016? This time they wanted to rotate my tyres for R3500 + because the brake fluid was changed, when I complained, the price came down to R350.00 to balance it. Since my car was serviced I had a tyre pressure sensor go on and my car adopted a intermittent, starting problem. I took it to Barons to do a diagnostic test R1009.00 guess what day 2 and they can't find anything wrong with my car, if they have to do anything else, it will be R1000.00+ to find a problem. I ask did you do a software update? No, did you check the body control module of the car? No. So I would like to know where do I go from here, I have to speak to Yolande, who is like the messenger, but when you collect your car, you must rate her service...I have rated the service before and nobody came back to me? So now I have paid R1009.00 for diagnostics but my car is still not fixed, where do I as a consumer stand? I asked if they contact VW SA to find out more info when they can't find a fault, the answer was no, so my car is limited to the knowledge of the diagnostics machine. My car is currently still at Barons N1 City, so I am waiting because it will start perfectly now, because the fault is intermittent.